Yuletarddecoriaitis
A person with the affliction which compels him/her to erect Christmas/Yuletide decorations ahead of Thanksgiving (in the United States of America) or the third Thursday of November each year (internationally).
Nancy just can't help it, she always has to put up her Christmas decorations before Thanksgiving; she has Yuletarddecoriaitis.
Yuletarddecoriaitis
An individual afflicted with the uncontrollable impulse to erect Christmas decorations and Yuletide spirit ahead of Thanksgiving (in the United Sates), the third Thursday of every November (internationally).
Nancy already has her Christmas tree and lights up and it's not even Thanksgiving! She must have Yuletarddecoriaitis. Poor thing.